(i) Technical Field
A certain aspect of the embodiments discussed herein is related to an optical modulation apparatus and a method for controlling an optical modulation apparatus.
(ii) Related Art
In an optical communication system that superimposes a signal on a light and transmits the light with an optical fiber, an optical modulator that modulates the intensity of a laser light emitted from a light source, and generates an optical signal is used. For example, a Mach-Zehnder optical modulator is widely known as the optical modulator.
The Mach-Zehnder optical modulator has a waveguide structure including a branch potion that branches an input light, two light waveguides that propagate the branched lights, and a multiplex portion that multiplexes the lights propagated through the light waveguides again. The Mach-Zehnder optical modulator is the optical modulator that turns on or off the light according to an interference condition at the time of multiplexing the lights.
In the Mach-Zehnder optical modulator, a technique that inputs a differential signal as a modulation signal to two light waveguides to perform a zero-chirp operation is known (see G. L. Li and P. K. L. Yu, “Optical Intensity Modulators for Digital and Analog Applications”, J. of Lightwave Technology, Vol. 21, pp 2010-2030, 2003).